suspension seatposts?

I am not opposed to the idea, and I am not condemning them. I just do not understand what they are for.

My take on suspension is that it is supposed to increase your control on the bike by keeping your wheels in contact with the ground. I can not see a benefit to a suspension seatpost other than comfort. as to the downsides they seem like they would add weight, and it also seems to me that you might get some bob under heavy seated pedaling. Although I have seen some pretty sweet bikes with the suspension posts on them (Buzzbomb's being the most memorable).

Can some of you suspension seatpost fans help me out? Do they add some level of control?

When I spied a deal on a RockShox suspension seatpost, my curiosity got the better of my wallet I didn't know what to expect, so I did multiple rides on the same trail with my old rigid and the RockShox (same saddle, height, seat angle). Very pleasantly surprised at the results. With the SSP my hardtail rides smoother, and I'm able to stay seated pedaling over medium-sized logs and roots I could not with the rigid post. I also seem to feel less beat-up after longer (10+ mile) rides. Don't get me wrong- the best SSP will NOT turn a hardtail into a dualie. IMHO- a properly tuned SSP fitted to a hardtail will clearly add comfort and a bit of control while seated.

Of course, some are better than others. I ride a thudbuster which moves you down and back instead of bobbing up and down.

i actually like moving around the saddle, rather than staying on it. i think its just a comfort issue not really control and if you are going through big bumps you shouldn't really be sitting on the saddle, really your legs should absorb most of the rough stuff

Yep, it's about comfort. It will let you stay seated for a lot of small stuff so you can keep hammering away, but you are still riding a hardtail, and need to come out of the saddle for the bigger stuff... I've been doing a few epic XC rides this summer, ranging from 60 to 100 miles (total mileage roads + trails), and my setup is super comfortable.